1. Field of the Invention
This invention generally relates to a camera system comprising a camera accessory such as, for example, an interchangeable lens or a lens converter, and a camera body to which the camera accessory is coupled and, more particularly, to a camera system operable by carrying data, stored in the camera accessory to the camera body. This invention also relates to an improvement in the camera accessory or the camera body or a combination thereof utilizeable in the camera system of the type referred to above.
2. Description of the Prior Art
There has been well known a camera system comprising a camera accessory adapted to be coupled to a camera body and provided with an information storing and memorizing circuit (hereinafter referred to as a ROM) which stores various pieces of information peculiar to the camera accessory (for example, the maximum and minimum aperture values of an interchangeable lens in the case where the camera accessory is the interchangeable lens), so that desired pieces of information of the camera accessory can be read in the camera body by specifying corresponding addresses in the ROM. However, the practical design of such a system involves numerous problems.
In the first place, in the system of the type described above, a plurality of coupling terminals are necessary to electrically connect the camera accessory with the camera body for the transmission of signals therebetween. A control circuit for controlling the transmission of the signals between the camera body and the camera accessory through the coupling terminals is also necessitated. However, in terms of the reliability, the smaller the number of the coupling terminals, the better. Yet, it is desired to render the signal transmission control circuit to be compact in structure. Moreover, since the signals to be carried from the camera accessory to the camera body are diversified, specific counter measures therefore are desired to be embodied. A counter-measures is also required to render the camera body to cope with the camera accessory having no data to be carried to the camera body when it is coupled to the camera body.
Hitherto, however, those problems have not been solved and, even if solved, are solved unsatisfactorily.